const defaultState={
	user:{
		username:"guest",
		password:"123456",
		back1:""
	}	
}
//Assign arrow function to a variable before exporting as module default
const t=(state=defaultState,action)=>{
	switch(action.type){
		case "user_signin_event" :
			let newState = JSON.parse(JSON.stringify(state));    //深拷贝
			newState.user=action.user;                           //dispatch action承载参数 
			return newState;
		default :
			return state;	
	}
}
export default t;